Draft control apparatus



June. 24, 1941. G. JANSEN DRAFT CONTROL APPARATUS 2 Sheefs-Sheet 1 Filed Feb. 10, 1939 Gerhard. Jansen June 24, 1941.

G. JANSEN 2,246,629

DRAFT CONTROL APPARATUS Filed Feb, 1Q, 1939 2 Sheets-Sheet 2 Gz'rhavd. Jans en Patented June 24, 1941 UNITED STATES PATENT ()FFICE.

DRAFT CONTROL AHPARATUS Application'February 10, 1939, Serial No. 255,594

4 Claims.

My invention relates to draft regulators and has for an object to provide an extremely simple and practical draft regulator capable of being used for maintaining a constant pressure or draft in furnaces or other heating plants.

An object of the invention resides in providing a draft regulator using a single pivoted vane which is actuated by draft variations and which automatically controls thedraft without the passage of outside air into the duct or smoke pipe with which it is associated.

Another object of the invention resides in constructing the draft regulator so that the vane is pivoted intermediate the edges thereof and in further constructing the draft regulator so that the vane on one face thereof is subjected to the draft in the duct or smoke pipe on both sides of the pivot and on the other face thereof so that one side of the vane is subject to atmospheric pressure and the other side subject to'the pressure in the smoke pipe or duct.

An object of l the invention resides in constructing the damper so that the moments of the pressures acting uponthe face of the vane, first referred to, are substantially equal.

Another object of the invention resides in providing a duct through which the flue gas passes and a housing associated therewith.

A feature of the invention resides in constructing the housing arcuate and in arranging the housing with its axis at a locality common to both the housing and duct.

A still further object of the invention resides in providing a pivot for the vane disposed at the axis of the housing.

Another object of the invention resides in arranging the vane so that it extends both into the duct and housing.

A feature of the invention resides in constructing the housing so that the same communicates with the duct on one side of the pivot and with the atmosphere on the other side of the pivot.

Other objects of the invention reside in the novel combination and arrangement of parts and in the details of construction hereinafter illustrated and/or described.

In the drawings:

Fig. 1 is a perspective view of a draft regulator r illustrating an embodiment of my invention.

Fig. 2 is a cross sectional view taken on line 2-2 of Fig. 1.

Fig. 3 is an elevational sectional view taken on line 3-3 of Fig- 1.

My invention comprises a duct it which, in the form shown in the drawings, is preferably cylindrical being provided with open ends H and I2. This duct has a passageway 30 extending therethrough, through which the flue gas flows.

The duct I is adapted to be inserted into the smoke pipe of a furnace or heating plant and is arranged so that the end H is connected to the portion of the smoke pipe leading from the furnace and the end I2 is connected to the portion of the pipe extending to the chimney. By this arrangement the flue gas travels from left to right in the direction of the arrow shown in Fig. 3. The duct 10 has a laterally extending opening iii in it, best shown in Fig. 3. Associated with the duct I0 is a housing M which is formed with a chamber 50 within the same. This housing is constructed with spaced parallel side walls It and it, which walls are tangent to the duct Ill at the opening 13 therein. The walls [5 and I6 may, if desired, be constructed integral with the duct l8 and have been so shown in the drawings. It can, however, be readily comprehended that these walls may be made separately and attached to the duct l0 in any desired manner. Associated with the two walls l5 and i6 is an arcuate wall 29. The wall 28 is constructed at its edges with flanges ll which are turned at right angles thereto and which are adapted to overlie the walls l5 and It. These flanges have openings in them which are adapted to receive tongues l8 formed on the walls It and IE. These tongues are bent over upon the flanges i1 and serve to hold the parts assembled. The wall 20 at its ends is constructed arcua-te to fit the duct 10 and at which locality said arcuate wall is provided with inwardly turned lugs l9 which, together, form a flange situated within the interior of the duct It. The lugs It may be spot welded to the duct Hi. The arcuate wall is so situated that its axis is substantially tangent to the duct [0.

The two side walls I5 and [6 are constructed with radially extending slits 2| which commence in close proximity to the axis of the wall and extend up to the said wall. The wall 20 terminates at the slits 2!. At this locality the metal of the walls l5 and I6 and the wall 20 at their free edges are turned inwardly to form flanges 22 which extend about the three sides of the housing It at the open end thereof. Connected to the edges of the portions 25 of the walls i5 and I6, which constitute part of the duct i0, is a plate 23 which extends completely across said portions and closes off the interior of the duct I 9. This plate is formed with flanges 24, at the edges thereof, which overlie the edges of the portions 25 and which may be secured thereto by means of spot welding. Plate 23 has a lip 26 at its innermost edge turned upwardly therefrom and which etxends up to the flanges 22. The plate 23 has bent at substantially right angles to it a portion 21 which forms an end wall for the portion of the duct Iii defined by the portions 25 of walls I and It. This end wall has flanges 28 which overlie the portions 25 and are spot welded thereto. The said wall further has lugs 3!, similar to the lugs I9, which lie upon the interior of the duct It) and are spot welded thereto. By means of this construction an opening 32 is provided in the housing M, which opening brings the interior of said housing into communication with the atmosphere through the slits 2i. At the same time the duct H! at the adjacent locality is closed. It will be noted that the housing M is also in communication with the passageway to of the duct it through the opening !3 previously referred to.

Within the chamber it of the housing i and the passageway 30 of duct ii] is disposed a vane 33. This vane has a rectangular portion 34 situated within the chamber 56 of housing 1-1, which portion fits closely to the walls l5, l3 and 26 of the housing. The said vane also has a curved portion 3'5 which fits loosely within the passageway 30 of duct IS and which serves as a damper for controlling the flow of gas through the duct. The vane 33 is pivoted by means of a shaft 36 which extends through loops 3? formed on said damper and which is journalled in bearings t l attached to the two side walls l5 and E5 of the housing i l. The axis of this shaft is situated at the axis of the wall 26 so that the portion 35 of vane 33 functions as a piston operating within the arcuate chamber 59 within the housing It.

Attached to the exterior of the shaft 33 is a sheave 4!. This sheave has attached to it a chain 42 which has secured to it a cotter pin G3. Mounted on the cotter pin 23 is a weight 4 3 and a number of washers 45 by means of which the mass of the weight on the chain 52 may be adjusted. The Weight 44 and washers 45 determine the draft flowing through the passageway 38 of duct Hi. The two portions 35 and 35 of the vane 33, on the face 56 thereof, which is the face directed to the chimney, are both subject to the pressure in the duct I 8 created by the draft in the chimney. These two portions are preferably designed so that the moments of the pressure exerted on the same are substantially equal, whereby the pressure on the suction or chimney side of the vane 33 has no effect in causing rotation of the vane, the forces produced thereby being equalized. It will, however, be noted that the face ii of the vane 33, which is the face directed toward the furnace, is subjected throughout the portion 35 of the vane to the pressure in the duct l 53 which is responsive to the pressure in the furnace. Similarly the pressure on the face 57 of the portion 34 of vane 33 is subject to atmospheric pressure. Said piston and damper portions 3 35 of the planiform vane 83 counterbalance each other, no additional vane balancing means being required extraneously of the vane per se, Additionally, it is to be noted that the centers of gravity of said piston and damper portions 3t, 35 of the planiform vane 33 not only counterbalance each other, but are in a common plane. Thus, the device will operate as intended in any disposition thereof that may be required in its application to a flue, it being understood, of course, that in certain positions of the device on its side, the chain 42 will require suitable guiding means between the sheave 4! and weight 44.

For the purpose of limiting the movement of the vane 33 two stops 49 and 5! are employed which are formed on a support 48. This support is spot welded to the wall 15 of case It near the center of the arcuate wall 25!. A pin 54 on the shaft $5 operates between the two stops 49 and Si and arrests movement of said shaft when the vane 33 reaches its extreme positions.

The operation of the invention is as follows: When the draft control apparatus has been installed with the smoke pipe leading from the furnace connected to the end H of duct If] and with the portion of the smoke pipe extending to the chimney connected to the end E2 of the furnace, the device will function as follows: A suitable weight is applied to the chain 42 which, when no draft occurs holds the vane 33 in the position shown in dotted lines at 38 in Fig. 3. As the draft in the chimney increases, the pressure of the flue gas against the portion 35 of vane 33 and upon the face 47 thereof decreases. The atmospheric pressure on the same face 4'! and the portion M of said vane therefore has the effect of rotating the vane in a clockwise direction, as viewed in Fig. 2. This brings the vane to an intermediate position, one such position being shown in full lines in Fig. 3. The moving of the portion 35 into this position serves to partially block the flow of fiue gas through passageway Bfi of duct l0 and thereby decreases the suction or draft in the furnace. A locality is reached at which equilibrium results. If the suction increases further, the vane moves in a clockwise direction until equilibrium is again reached. At-

such new locality the moments of pressure exerted are balanced so that the pressure at the furnace is again reduced to normal. The fully closed position of the vane 33 is shown in dotted lines at 39 in Fig. 3. It will thus be readily comprehended that the device automatically maintains uniform pressure in the furnace so that uniform operation of the heater, associated with the furnace results.

The advantages of my invention are manifest. An extremely simple and practical construction has been provided which automatically regulates the draft of the furnace. The device utilizes but a single shaft and a single moving member whereby friction is reduced to a minimum. Since the piston and damper portions 36, 35 of the vane 33 counterbalance each other, said vane requires no additional counterbalancing means. With my invention the housing enclosing the vane may be made as part of the duct through which the flue gas travels, thereby reducing the cost of manufacture. My invention can be constructed with machinery and equipment now available for the purpose and without appreciable investment or expense. The apparatus can be constructed at a nominal cost. Due to the fact that said piston and damper portions 34, 35 of the vane 33 have their centers of gravity in the same plane, the present device can be readily applied to existing smoke pipes in any position required, with either side or end uppermost, without appreciable alteration and in relatively confined localities, any such alteration in any such case simply requiring an additional guide for the chain 62. The open end of the housing M, through which the outer atmosphere has access to the piston portion 34 aeeacco of the vane 33, closely faces the duct to and provides an arrangement in which said open end of said housing is simply and effectively guarded by the duct structure. Furthermore, the thin slotlike space between said open end of said housing id and the duct structure provides a passageway which restricts the how of air into and out of the housing and clamps the pressure-induced move ments of said vane.

Changes in the specific form of my invention, as herein disclosed, may be made within the scope of what is claimed without departing from the spirit of my invention.

Having described my invention, what I claim as new and desire to protect by Letters Patent is:

1. In a device of the character described, a duct providing a passageway for flue gas, an

arcuate housing of substantially semi-circular extent bowing outwardly from a side of said duct, one end of said housing joining the duct and being open to the interior thereof and the other end of said housing terminating slightly short of said duct to provide a restricted slotlike passageway between the same and the adjacent side of the duct, said second end of said housing being open to the atmosphere through said restricted passageway, a pivot disposed axially of the housing, a substantially planiform vane mounted between its ends on said pivot, one portion of said vane at one side of said pivot providing a piston member within said housing and the other portion of said vane at the other side of said pivot providing a damper member within said duct, one face of said piston member being subjected to the pressure of the outer atmosphere through said second end of said housing, the other face of said piston member and both faces of said damper member being subjected to the pressure within the duct, said piston member and damper member being relatively proportioned substantially to equalize the moments of pressure exerted against them within said device, and means offering resistance to movement of the vane bringing the damper member into position obstructing said duct.

2. In a device of the character described, a duct providing a passageway for flue gas, an arcuate housing of substantially semi-circular extent bowing outwardly from a side of said duct, one end of said housing joining the duct and being open to the interior thereof and the other end of said housing terminating slightly short of said duct to provide a restricted slot-like passageway between the same and the adjacent side of the duct, said second end of said housing being open to the atmosphere through said restricted passageway, a pivot disposed axially of the housing, a planiform vane mounted between its ends on said pivot, one portion of said vane at one side of said pivot providing a piston member within said housing and the other portion of said vane at the other side of said pivot providing a damper member within said duct, one

face of said piston member being subjected to the pressure of the outer atmosphere through said second end of said housing, the other face of said piston member and both faces of said damper member being subjected to the pressure within the duct, said piston member and damper member substantially countenbalancing each other and being relatively proportioned substantially to equalize the moments of pressure exerted against them within said device, and means offering resistance to movement of the vane bringing the damper member into position obstructing said duct.

.3. In a device of the character described, a duct providing a passageway for flue gas, an arcuate housing disposed along a side of said duct, one end of said housing being connected with the duct and opening into the interior thereof and the other end of said housing being open to the atmosphere, a pivot disposed axially of the housing, an elongated vane mounted between its ends on said pivot, one portion of said vane at one side of said pivot providing a piston member within said housing and the other portion of said vane at the other side of said pivot providing a damper member within said duct, one face of said piston member being subjected to the pressure of the outer atmosphere through said second end of said housing, the other face of said piston member and both faces of said damper member being subjected to the pressure Within the duct, said piston member and damper member substantially counterbalancing each other with their centers of gravity substantially in the same plane and being relatively proportioned substantially to equalize the moments of pressure exerted against them within said device, and means offering resistance to movement of the vane bringing the damper member into position obstructing said duct.

4. In a device of the character described, a duct providing a passageway for flue gas, an arcuate housing disposed along a side of said duct, one end of said housing being connected with the duct and opening into the interior thereof and the other end of said housing facing the duct in near proximity thereto and being open to the atmosphere and guarded by said duct, a pivot disposed axially of the housing, a substantially planiform vane mounted between its ends on said pivot, one portion of said Vane at one side of said pivot providing a piston member within said housing and the other portion of said vane at the other side of said pivot providmg a damper member within said duct, one face of said piston member being subjected to the pressure of the outer atmosphere through said second end of said housing, the other face of said piston member and both ataces of said damper member being subjected to the pressure within the duct, said piston member and damper member being relatively proportioned substantially to equalize the moments of pressure exerted against them within said device, and means oifering resistance to movement of the vane bringing the damper member into position obstructing said duct.

GERI-IARD J AN SEN. 

